If that happens, then all the proffesionals (and not only them) will go to the Windows PC in order to work, because (as for now) the iPad is an expensive toy.
And although Apple sells more iPads than Macs, you should consider how many more Windows laptops are sold, something that proves that people are not convinced to replace the laptop with the tablet.
If the Mac and the macOS (especially the latter) is abandoned in favor of the iPad and the iOS, Apple will lose in the long run.
It is the Operating Sytem that makes all the difference, NOT the device. More and more people who don’t want Windows and can’t afford a Mac are turning to Linux which has the same stability and speed as the macOS. If more and more apps come to Linux (something that is happening although at a slow rate) then everyone will be able to have a cheap “Mac”.
